A/C isn't my strong suit either, but the following might help you figure it out...

E36 test functions.
The test functions for the 328 heating system. Here are how this feature works:
The IHKA of the 1996 E36 has a feature that allows different sensor values to be displayed on the control panel. The display mode is called up by pressing the "AUTO" and "REAR DEFOGGER" buttons simultaneously. 12 displays are available and you can toggle through them by pressing the fan rocker switch.